Sound radiator



Aug. 26, 1930. C E. .LANE 1,773,910

4SOUND RADIATOR Filsd Sept. 30. 1926 3 Sheets-Sheet l Aug. 26, 1930. c. E. LAN E 1,773,910

` soUND RADIATOR FlSd Sep'f.r 30. 1925 4 3 Sheets-Sheet 2 Aug`. 26, 1930.

C. E. LANE SOUND RADIATOR Filed Sept. 50, 1926 3 Sheets-Sheet 3 Patented Aug. 26, 1.930

UNITED STATES PATENT OFFICE CLARENCE E. LANE, 0F MONTCLAIR, NEW JERSEY, ASSIGNOR T0 BELL TELEPHONE LABORATORIES, INCORPORATED, 0F NEW YORK, N. Y., A CORPORATION OF NEW YORK SOUND RADIATOR Application led September 30, `1926. Serial No. T 38,620.

This invention relates to sound radiators and particularly to the type in which a large vibrating structure radiates directly into the air.

An object of the invention is to radiate sound energy with substantially uniform efficiency over at least a large portion of the entire frequency range of speech and music.

The ideal sound radiator is one which emits sounds with uniform efficiency over the entire audible frequency range. The higher frequencies are especially important in reproducing speech since some of the consonant sounds have a large portion of their energy at the higher frequencies, for instance the sounds z, th, and s have a substantial portion of their energy at a frequency range above 5,000 cycles per second. The low frequencies on the other hand, are necessary for the faithful reproduction of music. The sound radiator of the present invention responds to the higher speech frequencies as well as the lower frequencies of the audible range, and has a fairly uniform frequency response characteristie.

In accordance with the invention, in a broadaspect, there is provided a large diaphragm which is hinged to a support at al peripheral. portion and is driven at a portion remote from said hinged portion. In one embodiment of the invention, the diaphragm, which is preferably made of paper or other light material corrugated vertically and reinforced by horizontal stiffening ribs of wood or other light material, is hinged to a support at two opposite ends and driven by an electromagnetic element secured to stifl'ening ribs positioned remotely from the hinged portion of the diaphragm. The material, of which the diaphragm is made, eX- tends, at each side edge. beyond the stiffening ribs to form flexible members which are attached to the upright portions of the stand or frame. The diaphragm may form a side of an enclosed air chamber, which may be one of a plurality of such air chambers, serving to effectively increase the mass of the diaphragm at low frequencies while at higher frequencies these enclosed spaces may serve as resonant chambers. The structure occupies very little space in the direction perpendicular to the plane of the diaphragm and may, therefore, be easily fitted into a wall or cabinet.

The invention may be more clearly understood by referring to the accompanying drawing in which:

Fig. 1 is a front view of one embodiment of the invention,

Figs. 2, 3 and 4 are sectional views taken along the lines 2 2, 3-3 and 4-4 of Fig. 1,

Fig. 5 is a diagrammatic showing of the wave propagation along a diaphragm of the type shown in Fig. 1,

Fig. 6 shows variously shaped diaphragms which may be employed in connection with this invention,

Figs. 7 and 8 are front and side views. respectively, of a modified form of the structure shown in Fig. 1,

Figs. 9 and 10 are sectional views taken along the lines 9-9 and 10-10, respectively of Fig. 7,

Figs. 11 to 13 show the invention in a form which is adapted to be set into a Wall of a room, Fig. 11 being a perspective view partly in section and Figs. 12 and 13 being sectional views showing two different embodiments of the invention of the general form shown in Fig. 11, and

Fig. 14 is a diagrammaticshowing of the wave propagation along a diaphragm of the type shown in Figs. 7 and 11.

eferring particularly to Figs. 1 to 4, inclusive, of the drawing, the rectangular shaped diaphragm 20 in a preferred form is made of crimped., pleated or corrugated fleX ible material and is preferably at least a square foot in area although it may be smaller. The diaphragm is reinforced by the stiffening ribs 21 and is connected to the frame 22 by the hinge-like members 23 which are preferably more flexible than the diaphragm. The stiffening ribs 21 in a preferred form are made of flat strips of wood or other light material having an edge formed to fit into the corrugations of the diaphragm to which the strip may be glued or otherwise secured. The driving element 24 is secured to the frame 22 by means of the upright angular bars 25 and phragm. Instead 0f having one large diaphragm about the size of the opening in the wall, two diaphragms of the same width but half the length of the opening may be employed. In this case one diaphragm is preferably hinged at the top of the opening and the other at the bottom, the edges opposite the hinged sides being adjacent near the midportion of the opening and being driven by a common actuating device or several actuatin'Y units preferably driven in synchronism. single diaphragm of the type shown in Fig. 1 may also be employed, such a diaphragm being substantially equivalent to two diahragms joined at their adjacent edges, i -nged at `the opposite edges, and driven along a stiffcning rib positioned between the two hinged portions.

The embodiment of the invention shown in Fig. l1, aside from its practicability as an eiiicient and faithful reproducer of sound, is readily adaptable to the art of interior decoration. For this purpose a decorative screen of wire, sheet or molded metal, or carved wood may be used. Where desired, a screen of this sort may be used only for protecting the diaphragm and a hanging of silk, tapestry or other material may be used, over the screen, as a decoration. As shown in the drawing a protecting screen 83 and a decora` tive hanging Si, preferably of light. material, are attached to the frame 73 which lits into the frame 75. TvVhen employing rather heavy hangings, it is preferable to have the 3er portion of the frame 73 project slightly beyond the other edges of the frame and the liront of the wall and to attach the hanging 84 to this projecting portion so as to avoid excessive damping of the radiated sound .vave Material of relatively light weight may, however, be stretched across the frame shown.

ln Fig. 13 the sound radiator is shown inserted in a wall between two adjoining rooms, in which vcase two frames 7 3 and their associated hangings 84 are employed, one on each side of the diaphragm. The sound radiator may also be employedk in a wall which is closed up at its inner side as shown in Fig. 12. With this arrangement the enclosed space at the back of the frame mayy serve as a resonant chamber for accentuating certain frequencies.

lVhile the exact mode of vibration of a diaphragm constructed in accordance with this invention has not been determined and while the invention is independent of the theory of operation,l it seems very probable that the correct explanation of the operation of the improved diaphragm which accounts for the superior results obtained with it, is as follows: Considering irst a low frequency force applied by the driving means to a. diaphragm of the type shown in Fig. 7, the diaphragm will move substantially as a unit about the hinged portion as indicated at a of Fig. 14. At considerably higher frequencies 'the driving force sets up a wave motion in the diaphragm structure. his wave, which is initiated at all points along the upper edge of the diaphragm simultaneously, is

propagated toward the hinged portion at a velocity dependent upon the elasticity and mass of the structure and is attenuated or damped as it progresses. The rate of damp` ing, with respect to the distance traveled by negligible radiation is at a relatively short distance from the top of the structure. These conditions are diagrammatically represented at b and c, respectively, of Fig. le. The diaphragm structure is given very great ness and small mass so that at the higher frequencies of the speech and music range the wave has greater amplitude and is propagated a greater distance and therefore in volves a larger area` of the diaphragm strueture than would be the case if the stiffness were less or the mass greater. Furthermore, the driving force is applied not at a single point but simultane zsly at all points sions; the upper edge of the diaphragm, which li wise increases the area of tl e diaphrawi which is brought into active service at the higher frequencies, as compared with arrangements in which the driving force applied at a single point or along a relatively short line.

fis stated above the diaphragm of the type shown in Fig. 1 differs from the one shown in Fig. 7, essentially in that the former consists in effect of two diaphragms of the latter type joined and driven along the eopposite the hinged portion, but these c phragms also differ from each other in the type of hinge employed. The diaphragm the structure shown in Fig. 1, beez use of the type of hinge employed and also because oi' the relatively large degree of stiffness at the driven portion of this diaphragm in the direction perpendicular to the stiiening ribs moves substantially as a unit at low f. quencies, that is, all portions of the phragm are displaced equally as shown a of Fig. 5. At higher frequencies, the diaphagm vibrates as indicated at l), c and. d of Fig. 5, these diagrams being Ithe saine as tho shown at a, b and c of Fig. 14 except that i Fig. 5 the waves are shown traveling in both directions from the driven port-ion toward the two hinged members.

@ne effect which the enclosed air cham bers, shown in Fig. 2, have upon the fre- Cil L i nagm having ratio oi in s resonant at a lon7 vtrequenc'y7 tlre the diaphragm lon* frequencies i` L`ed due to the addition ot the i i to the mass ot the diaphra quencies the d h unit but breahs into Waves shown at c and a? of Fi 5. or this condition there is no tendency igor the diaphragm to more the mass of the enclosed air as a unir and, therefore, the mass o the diaphragm is not effectively increased as is the case at lower frequencies. These air ciaiibers, hone 'er7 mayv be t srch sine tnat theiT resonan to Waves of re 'eh frequency. rlhe two eiieets then, mai,v serre to increase tl efficiency of the dialihragm at both thU uppe and lower ends or he sound :frequency range.

in order to i ree simulcn porcessarr that the nlieible. To

ons bec ns Way phragm is apit of the st-iiiening ribs even though the dia phragm is driven along a relatively short line.

it Will be clear from what has just been stated that an advantage may sometimes he gained by varying the shape of the dia- "agggm structure to eliminate the outermost cent the stiifcning rib to which riif'ing i'orce is appned. This is shown .nd e ot Fig. Furthermore, the rela iciency at Various frequencies through- 'ie range may be moditied by otherwise shape oi the diaphragm as shown Ae at 31,0 and /Z ot Fig. 6. The stiflma i be rariansiav positioned and ai, 'o assist ii obtaining a desired transon characteristic. iile the drawings show a substantially ilario, corrnnja ed diaphragm of yariety oit e to be iniderstooeL lthat the scope frition includes diaipihragms made ier sl'iapes and iforms than shown L and iarious other m xans -for O the oiaphragm. For example, the n jv l curved rather than plane `ripherj7 may he circular or elliptifrm direct ac ingr diaphragm7 is claims to signify a diaph agin directly.' upon the unrestricted Y inni into which it radiates. g claimed is:

sound radiator comprising' a direct ne corrugated diaphragm hinged p irtion to a supporting` to drive said diaphragn'i at i te i'rom said hinged portion.

r irtor comilirising)r a directI d' ragni hinged at a pe- ,iann Aion to a supporting means7 and e ail diaphragn'i at a portion i t in l hinged portion. sound radiator comprising a flat d'apliragm at least ono square toot ringed at a perilfiheral portion to a A means, and aetnatingr means to rive said diaphragm at a portion remote nged portion.

rdiator comprising; om or iexihle corrugated a plane material supportapli-.ra hinged at a igieripheral portion to a n ine-ans, stitleninpf ribs tor said diaphragm ,Norse to the coir i ns in said matec us to drive said diaa portion remote from said hinged and :etna nhrigm at Si sound raoiator comprising a direct a diaphragm hinged at a peripheral portion to a supportingr means, flexible memher," attached to said diaphragm and to said snpaortine' mea or, in part at least, closing the opening therebetween, and actuating` means connected to said diaiihralm to drive it at a portieri remote from said hinged portion.

sound radiator comprising a diaphragm of flexible corrugated material inged at a peripheral portion to a supporting means, a plurality of stiffcning ribs attached to the diaphragm and extending in an angular direction with respect to the direction of said corrugations, flexible members attached at one edge to said diaphragm and at the other edge to said supporting means, and actuating means connected to the diaphragm to drive it at a portion remote from said hinged portion.

7. A sound radiator comprising a diaphragm, a support, a hinge along at least one straight edge of said diaphragm between said diaphragm and said support, spaced stiifening ribs for said diaphragm parallel to said hinge, and driving means the vibrating element of Which is attached to at least one of said ribs.

8. A sound radiator comprising a diaphragm, a support, a flexible hinge along at least one straight edge of said diaphragm connecting said diaphragm With said support, spaced stitfening ribs for said diaphragm parallel to said hinge, said ribs assisting in giving said diaphragm a. fairly constant transmission characteristic over a Wide range of frequencies, and driving means the vibrating element of Which is attached to at least one of said ribs.

9. A sound. radiator comprising a diaphragm of relatively light corrugated material, a support, a flexible hinge along atleast one straight edge of said diaphragm connecting said diaphragm to said support, spaced stiilening ribs for said diaphragm parallel to said hinge, said ribs cooperating With the corrugations of said material to assist in giving said diaphragm a fairly constant transmission characteristic over a Wide range of frequencies, and driving means the vibrating element of Which is attached to at least one 0f said ribs.

10. A sound radiator comprising a diaphragm, a support, a flexible hinge along a straight edge of said diaphragm connecting said diaphragm with said support, a stiftening rib parallel to the hinge, and driving means the vibrating element of which is attached to said. stiffening rib.

11. A sound radiator comprising a corrugated diaphragm, a plurality of stiifening ribs attached to said diaphragm and extending in an angular direction with respect to the direction of said corrugations, a supporting means near a peripherial portion of said diaphragm, and means attached to at least one of said stiffening ribs for actuating said diaphragm.

12. A sound radiator comprising a diaphragm of flexible corrugated material hinged to a support, stiifening ribs for said diaphragm shaped to fit into the corrugations of said diaphragm, and actuating means the vibrating element of which is attached to at least one of said stitlening ribs.

13` A sound radiator comprising a diaphragrn of flexible corrugated material hinged to a support, parallel stitfening ribs attached to said diaphragm, an intersecting rib for connecting at least two of said parallel stiifening ribs, and means attached to said intersecting rib for driving said diaphragm along said parallel ribs.

14. A sound radiator comprising a diaphragm of flexible corrugated material having stiffening ribs attached thereto, substantially U-shaped hinged members, the bases of which are attached to an edge of said diaphragm substantially parallel to said stiftening ribs, projecting members forming a part of said U-shaped hinged member for securing said hinged member to a support, and actuating means for driving said diaphragm along one of said stifl'ening ribs.

15. A sound radiator comprising a diaphragm of flexible corrugated material, stiffening ribs attached to said diaphragm extending substantially perpendicular to the corrugations of said diaphragm, a substantially U-shaped hinged member extending substantially parallel to said stiifening ribs for connecting a peripheral portion of said diaphragm to a support, driving means secured to a portion of said diaphragm remote from said hinged member for moving said diaphragm substantially as a unit at low frequencies.

16. A sound radiator comprising a stiffened diaphragm, llexible hinge members for connecting a peripheral portion of said diaphragm to a support, means for driving said diaphragm at a portion remote from said hinged members, and enclosed air spaces, one side of Which is formed by said diaphragm, for effectively increasing the mass of said diaphragm when driven at relatively lovv frequencies.

17. A sound radiator comprising a stiffened diaphragm, substantially U-shaped hinge members for connecting said diaphragm to a support, means for driving said diaphragm substantially as a unit at low frequencies and for setting up Waves in said diaphragm at substantially higher frequencies, and adjacent air chambers at least partially enclosed by flexible material, one of said air chambers being partially enclosed by said diaphragm, said air chambers assisting in giving said diaphragm a fairly constant transmission characteristic over a Wide range of frequencies.

In vWitness whereof, I hereunto subscribe my name this 28th day of September, A. D.

CLARENCE E. LANE. 

